NA exhaust diameter

[Pandamonium]

The standard centre section of the exhaust on the gls is on its way out and mot is up soon.

Just wondering whats the best diameter to get for the na engine for power etc?

It will eventually get a back box to match once i sort the back end of the car.

Cheers

[Amjad]

2"

[Pandamonium]

Legend cheers mate, sounds good.

What you running on yours? cats wise etc too

[raffa_mk]

2.5" especially if your ever thinking of fte in the future ;)

[Pandamonium]

Na cant see an fte in this one mate

[raffa_mk]

Na cant see an fte in this one mate

still 2.5" is better lol, and you can get your excisting back box welded on with a 2.5" to 1.75" reducer? and always fit a better back box later, my mate might have blitz nur spec one available too.

[Amjad]

2.5" is overkill on a small NA engine, you need back pressure whereas on a turbo car you don't

I've got a 2" cat-back with no silencers to a 3.5" back box. Loud but sounds bloody good

If you need a quiet car and you do a lot of miles keep a centre silencer and it should be good enough!

[raffa_mk]

2.5" is overkill on a small NA engine, you need back pressure whereas on a turbo car you don't

I've got a 2" cat-back with no silencers to a 3.5" back box. Loud but sounds bloody good

If you need a quiet car and you do a lot of miles keep a centre silencer and it should be good enough!

its no over kill if you got other mods, works a treat on my n/a just ask the people who know my car lol sounds awesome with 4.5" backbox

but yeh, if its quite and sensable one your after then 2" is good.

[Pandamonium]

Raffa have you had yours rolling roaded?

I know its only half an inch difference but dont want to lose too much back pressure.

Will be running rolla manifold, k+n panel filter, uprated sparks and leads

Bit of back pressure works great on the turbo too, GT spooled better with the standard centre section than whats on her now.

Ta

[Asad]

I thought the standard was smaller than 1.75"? Id go for the next size up 2.5" is too big on a N/A especialy for a standard head setup regardless of how "sick" it sounds

[Pandamonium]

Cheers chaps, leaning towards the 2" at the min then, and sort the back box at a later date

[raffa_mk]

Raffa have you had yours rolling roaded?

I know its only half an inch difference but dont want to lose too much back pressure.

Will be running rolla manifold, k+n panel filter, uprated sparks and leads

Bit of back pressure works great on the turbo too, GT spooled better with the standard centre section than whats on her now.

Ta

yeh i have had it on dyno with following setup and got 90.4bhp

k&n panel filter

Corolla injectors

Corolla exhuast manifold

Glanza inlet manifold

200 cell sports cat

2.5" cat back straight through with 4.5" back box

graphs below

I thought the standard was smaller than 1.75"? Id go for the next size up 2.5" is too big on a N/A especialy for a standard head setup regardless of how "sick" it sounds

haha it really is about the sound but on a serious note it is so free flowing and just feels so good, i was going to go 2" but decided to go 2.5" and never will turn back ;)

Edited March 11, 2012 by Raffa_MK

[Pandamonium]

Interesting, thats a nice result.

Cheers for that info

[raffa_mk]

The main differences I noticed from the cat back system was the restriction in the exhaust especially top end when it come to motorway driving especially when going 90plus

My exhaust is loud and that's the way I like it and if am going a long journey exhaust bung does the job perfect and cost only £15 when I had mine made up.

[raffa_mk]

Here's what it sounds like,

Link below

/>http://www.youtube.com/watch?v=0KEXqj9dytw&feature=youtube_gdata_player